Questions tagged [computational-geometry]
Computational geometry is the study of solving geometric problems using efficient algorithms and data structures, often in real time.
67 questions
0
votes
1
answer
58
views
Is an assumption of Welzl’s algorithm valid?
The stated assertion that a point outside some intermediate Minimum Enclosing Sphere is on the boundary of the final Minimum Enclosing Sphere seems unsupportable. It is true only for the first point ...
1
vote
0
answers
104
views
Page curl effect
I am trying to simulate a page curl effect in my custom OpenGL based rendering engine.
I initially implemented the version described in the paper "Turning pages of 3D electronic books" where ...
- 153
0
votes
0
answers
59
views
Shadow mapping frustum fitting based on Y=0 plane
I am trying to calculate tight fitting of shadow map texture based on camera frustum. Since the camera is always going to be looking down on the Y=0 plane, I ...
- 133
0
votes
1
answer
112
views
Variable subdivision creating artifacts
I'm currently implementing a method for subdividing an icosahedron found here that isn't quite working as expected due to the artifacts created (and the way the triangles are oriented)
The problem ...
- 47
1
vote
2
answers
110
views
Missing faces at ends of voxel chunks
I'm having problems generating faces in a chunk in OpenGL C++. For example, when I generate faces, they are generated correctly but always at the end of the chunks some faces are not generated.
...
0
votes
0
answers
108
views
How to make a hole of N vertices in the face of a Cube
I want to make a hole of N vertices in the face of a Cube, I'm adding just four like a square in this post to be simple, but eventually I want to be able to add as many as I want and maybe in a ...
2
votes
0
answers
400
views
Wrapping a mesh around another
I want to add LED strips to objects at runtime. The led strip is a very simple rectangular mesh that is generated at runtime. A shader then just draws LEDs down the length of the strip.
Here is an ...
- 77
1
vote
0
answers
46
views
Move a non-convex polygon's outline inwards?
The polygons are small 3D parts of a quasi sphere centered in the origin and a solution that works in the plane can easily be made to work in this world.
I tried to move the outline inwards by using ...
- 11
0
votes
1
answer
122
views
How to improve performance of code for finding climbing annotations?
The goal is to be able to climb any ledge, even if the ledge is an odd shape. Therefore, I found a script that searches for viable "climb holds" along any mesh of any shape. You can then use ...
- 3
1
vote
1
answer
122
views
How can I remove unnecessary vertices from wall edges?
I've got a pretty simple tile based 2d top-down map with an array of walls. In order to figure where to cast light and shadows, I've generated an array of vertex coordinates along the walls like so:
...
- 11
1
vote
1
answer
108
views
Unprojeting a line on the screen
I have a line connecting two points of my model. I see a projection of this line on my screen and a want to map a point of that projection to the corresponding point in my model PoV.
Let ...
- 11
0
votes
1
answer
276
views
Recalculating normals on a tesselated cubed sphere with heightmap applied
I'm learning about the graphics pipeline using C++, HLSL and DirectX 11 for my course. I'm currently tesselating a cubed sphere with an applied height map.
My issue is figuring out how to recalculate ...
- 25
0
votes
2
answers
191
views
Detect walls in geometry
Is it possible to automatically detect walls in polygon soup?
Of course it's hard to strictly define what a wall is, my slightly vague definition would be:
A wall is a largest possible box (not ...
- 407
3
votes
2
answers
12k
views
How to calculate the surface area of a mesh
I am looking for a way to calculate surface area of a 3D mesh object and found this code from a Unity forum:
...
- 2,074
0
votes
0
answers
72
views
Decompose a Mesh so that each piece can be watched by a Guard inside the piece
The title pretty much explains it but I'm gonna go into more details.
We have 3D mesh object and we want to decompose it into separate objects so that each one of these objects can be seen completely ...
- 123
3
votes
4
answers
196
views
Detecting single circle within multiple circles area
There are multiple circles with same radius, given another circle in different radius, how to detect the another circle is fully in multiple circles area.
Image below shows left samples is in the ...
- 49
1
vote
1
answer
204
views
Intersection of two limited planes (stripes)
Have two limited planes. That means just squares or stripe in 3D space (or two connected triangles on the same plane).
What I want to know is exactly how (and whether) they collide.
My first approach ...
- 165
4
votes
4
answers
522
views
Image-Space coherence of the z-buffer algorithm
I'm reading Hierarchical z-Buffer Visibility by Ned Greene et al. and they state that
traditional Z buffering makes reasonably good use of image-space coherence in the course of scan conversion.
I ...
- 55
5
votes
2
answers
482
views
How to find out the vertices of the polyhedron formed by the overlapping area of two rotated boxes?
What is the most efficient way for finding out the vertices of the polyhedron formed by the overlapping area of two rotated 3D boxes?
If it is still confusing what I mean by "polyhedron formed by...",...
- 4,927
0
votes
1
answer
1k
views
Generate Mesh of Shadow Volume
Given a mesh, I want to generate another mesh that is effectively a shadow volume of this mesh.
I am looking for an algorithm/solution/implementation/reference that can do this under the following ...
- 111
6
votes
2
answers
6k
views
How to construct the marching cubes tables algorithmically?
I want to implement the marching cubes algorithm from scratch, but I'm stuck at the polygon generation phase (building edge loops with correct orientation and triangulating them).
Obviously, I should ...
26
votes
8
answers
83k
views
How to calculate corner positions/marks of a rotated/tilted rectangle?
I've got two elements, a 2D point and a rectangular area. The point represents the middle of that area. I also know the width and height of that area. And the area is tilted by 40° relative to the ...
- 395
7
votes
1
answer
16k
views
Sphere-Sphere intersection and Circle-Sphere intersection
I have code for circle-circle intersection. But I need to expand it to 3-D.
How do I calculate:
Radius and center of the intersection circle of two spheres
Points of the intersection of a sphere and ...
- 253
3
votes
2
answers
317
views
Reconstructing mesh from topological skeleton?
I have a topological skeleton of a 3d maze-like level (think Descent[I]/II). It looks like a tree where each node is a vertex in 3d-space.
If it were on a 2d plain, I would "simply" use this to ...
- 10.6k
13
votes
1
answer
18k
views
Quads Vs Triangles
I'm curious to know which is better for games: quads or triangles? Wouldn't quads be better for rendering performances and smoothing out tessellation?
- 199